Prior art off-road bicycles include one in which the front wheel is supported by a front wheel suspension having a buffering mechanism and an attenuating mechanism, as disclosed in Japanese Patent Laid-Open Publicaiton H2-231289. This front wheel suspension comprises a steering bracket rotatably supported in a front portion of the bicycle frame, and a pair of front fork assemblies coupled together by the steering bracket. Each of the front fork assemblies includes an inner tube and an outer tube, which are slidable relative to each other. In these tubes, an oil chamber and a gas chamber are formed. Gas in the gas chamber functions as a buffering mechanism, and the oil chamber is provided with an attenuating mechanism.
With this prior art front wheel suspension, when the front fork assemblies are elongated and contracted by impact forces transmitted from the front wheel, the gas in the gas chambers in the front fork assemblies functions to absorb the impact forces, while attenuating forces that are generated as the oil in the oil chambers flowing through the attenuating mechanisms suppress the elongating or contracting motion of the front fork assemblies to suppress vibrations.
In the above prior art front wheel suspension, it is desirable to permit adjustment of the attenuating forces of the attenuating mechanisms in order to provide for a desired level of comfort depending upon the taste or weight of the individual driver.
However, if it is intended to permit adjustment of the attenuating forces for both the contraction and elongation of the front fork assemblies, the number of components is increased, and the construction of the attenuating mechanisms becomes complicated. Particularly, in a light weight bicycle, the diameter of the front fork assemblies is small, and it is thus difficult from the design standpoint to permit adjustment of the attenuating forces of the attenuating mechanisms for both the elongation and contraction of the front fork assemblies.